In our aforesaid earlier copending application, we have disclosed an applicator unit which is adapted to be moved through a field of growing vegetation, for instance as an implement mounted across the front of a farm tractor. The unit includes a horizontal, laterally extending outlet manifold ranked above a similarly arranged inlet manifold. Between each manifold a plurality of forwardly convex knee-like non-porous rod members are mounted. In use, a treatment liquid to be directly applied to vegetation is arranged to run out of the outlet manifold in a superficial sheet along the external surface of each rod. As vegetation is grazed by the rods, some of the treatment liquid is wiped onto the vegetation. Any treatment liquid which is not thus wiped onto vegetation is collected from the lower ends of the rods into the inlet manifold and pumped back up to a reservoir from which it flows to the outlet manifold. By preference each knee-like rod is disposed at an incline as seen in front elevation in order to decrease the chance that a tall thin plant can pass untreated between two adjacent rods. A valving system is provided to prevent air entry on inlet side of the pump.
The shortcomings of prior art systems for applying liquids to growing vegetation, including spray systems, mopping and wiping systems, especially those using wicks, and atomizer, mist and fogging systems are discussed in greater detail in our aforesaid earlier copending application.
As further development work leading to commercialization of their invention has been undertaken, the inventors have devised ways and means for further improving the apparatus and method which is disclosed in their aforesaid earlier copending U.S. patent application.